Comandos_Cisco_Parte 1

Troubleshooting, Editing, Port #’s

show ip interface brief (display interface designations, IP address and status)

show ip route (display routing table)

show vlan brief (on switch – show what VLANs exist, names, ports assigned )

show controllers serial x/x/x (see if DCE or DTE connected and if clockrate is present)

show interface trunk (what ports are trunking, native vlan, allowed vlans)

show running-config (display the running configuration – active)

show startup-config (display the starup configuration)

show ip protocol (what routing protocol, which networks, passive interfaces, neighbors)

show cdp neighbors (see directly connected Cisco devices)

show cdp neighbors detail (includes IP address at other end)

show cdp interface (which interfaces are running CDP)

show interface serial x/x/x (what encapsulation, IP address, counters)

show interface fastethernet x/x switchport (configured mode and operating mode)

show version (which IOS, capability, memory, configuration-register)

show run | begin interface (will start listing at the first instance of ‘interface’)

show ip route connected (show routing table entries for directly connected networks)

show ip route static (show routing table entries for static routes)

show ip route ospf (show routing table entries learned through OSPF)

show ip route eigrp (show routing table entries learned through EIGRP)

show mac-address-table or show mac address-table (varies with different IOS)

show flash (display filenames and directories in Flash memory)

show clock (current date/time in this device)

show ipv6 ??? (does the IPv6 version of many IPv4 commands)

show processes (shows active processes running on router)

show process cpu (shows cpu statistics)

show memory (shows memory allocation)

show users (show who is telnetted into this device)

show standby (see if HSRP is active)

ping X.X.X.X (try to reach the destination host at X.X.X.X)

trace X.X.X.X (show the path taken to reach the destination host at X.X.X.X)

R1(config)# do show ??? (execute show commands from configuration mode)

debug ??? (real-time reporting about processes related to almost any function)

debug all (very dangerous as the router can become consumed by reporting everything)

undebug all (turn off all debugging commands – handy if this is a busy router)

 Line Editing Commands

ctrl-a (go to the beginning of the current line)

ctrl-e (go to the end of the current line)

ctrl-p or up-arrow (repeat up to 10 previous commands in the current mode)

ctrl-n or dn-arrow (if you have gone back in command history, this moves forward)

backspace-key (erase the character to the left of the current cursor position)

ctrl-z or end (go out to privilege mode)

exit (move back one level in the hierarchical command structure)

ctrl-c (cancel current command or leave Setup mode if you accidentally get into it)

ctrl-shift-6 (stop ping or trace)

terminal length 0 [zero] (turn off paging – makes output without breaks)

terminal length 24 (normal page breaks in output)

wr (shortcut for ‘copy running-config startup-config)

 Common Port Numbers and Protocols

File Transfer Protocol (FTP)

FTP Control=TCP port 21

FTP Data = TCP Port 20

Secure Shell (SSH) – TCP Port 22

Simple Mail Transfer Protocol (SMTP) – TCP Port 25

Domain Name System (DNS) – TCP/UDP Port 53

Dynamic Host Configuration Protocol (DHCP)

BOOTPS=UDP Port 67 (DHCP request from client to server)

BOOTPC=UDP Port 68 (DHCP reply from server to client)

Hypertext Transfer Protocol (HTTP) – TCP Port 80

Post Office Protocol – incoming mail (POP) – TCP Port 110

Network Time Protocol (NTP) – UDP Port 123

Simple Network Management Protocol (SNMP) – UDP Port 161

Secure Hypertext Transfer Protocol (HTTPS) – TCP Port 443

Basic Router / Switch Configuration

 To Restore a Switch or Router to Default Configuration

 S1# delete vlan.dat (hit ‘enter’ to accept defaults) [Note: Only do this on a switch]

 S1# erase startup-config (hit ‘enter’ to accept defaults [Router or Switch])

 S1# reload (answer ‘no’ if asked to save current config [Router or Switch])

 Router / Switch Basic Configuration

 R1# configure terminal (enter global configuration mode)

R1(config)# hostname NAME (configure the NAME of the Router or Switch)

R1(config)# security passwords min-length 5 (set minimum password length)

R1(config)# service password-encryption (encrypt all passwords – except secret)

R1(config)# login block-for 60 attempts 3 within 30 (wait 1 min if 3 bad attempts in 30 s)

R1(config)# enable secret PASSWORD (make the privilege level password ‘PASSWORD’)

R1(config)# no ip domain-lookup (suppress DNS attempt when a command is mistyped)

R1(config)# banner motd MESSAGE (create a MESSAGE that will display when logging in)

R1(config)# line console 0 [zero] (enter the console connection configuration mode)

R1(config-line)# password PASSWORD (make the user level password ‘PASSWORD’)

R1(config-line)# login (instruct the router that you want it to check for a password)

R1(config-line)# logging synchronous (assists by keeping command entry more orderly)

R1(config-line)# exec-timeout 0 0 [zeroes] (no timeout while configuring the router)

R1(config)# line vty 0 4 [zero 4] (configure the same options as line console above)

S1(config)# line vty 0 15 [zero 15] (configure the same options in a switch)

R1# copy running-configuration startup-configuration (save config in NVRAM)

R1# wr (legacy command – Same as copy running-configuration startup-configuration)

R1(config)# ! (remark – makes no configuration changes)

 For Switch Management Interface Configuration

S1(config)# interface vlan 1 (create a virtual host on the switch)

S1(config-if)# description Management interface for this switch (optional description)

S1(config-if)# ip address (assign an IP address)

S1(config-if)# no shut (must turn it on)

S1(config-if)# exit (leave interface config and return to global config)

S1(config)# ip default-gateway (must be on same subnet as Mgt interface)

S1(config)# enable secret class (must have an enable password for remote config)

S1(config)# line vty 0 15 (switches may have 16 VTY connections at once)

S1(config-line)# password cisco (must set a login password for telnet to be possible)

S1(config-line)# login (tell the VTY ports to ask for password from remote user)

S1(config-line)# transport input telnet (allows only telnet for remote config – default)

Configuring IPv4 Router Interface

R1(config)# interface INTERFACE-TYPE (enter configuration mode for an interface)

R1(config-if)# ip address ADDRESS SNM (assign the IP Address and subnet mask)

R1(config-if)# description WORDS (document what this interface is used for)

R1(config-if)# clock rate CLOCK (on serial DCE interfaces, set the speed of the link)

R1(config-if)# bandwidth VALUE (used by the routing protocol for the speed of the link)

R1(config-if)# no shutdown (turn the interface on)

R1(config-if)# shutdown (turn the interface off)

 Configuring IPv6 Router Interface

R1(config)# ipv6 unicast-routing (activate IPv6 routing – off by default)

R1(config)# interface Gi1/1

R1(config-if)# ipv6 enable (turn on ipv6 in this interface)

R1(config-if)# ipv6 address 3ffe:b00:c18:1::3 /64 (manually enter complete address)

R1(config-if)# ipv6 address 3ffe:b00:c18:1:: /64 eui-64 (auto configure host portion)

R1(config-if)# ipv6 address fe80::4 link-local (configure link-local address)

 Layer-3 Switch Commands

S1(config)# ip routing (activate IPv4 routing within the switch)

S1(config)# ipv6 routing (activate IPv6 routing within the switch)

S1(config-if)# no switchport (used to designate that this is a router port, not a switchport)

S1(config-if)# switchport trunk encapsulation dot1q (to configure trunking for dot1Q)

 VLANS, Trunks, Router-on-a-Stick, VTP

 VLAN Creation and Port Assignment

S1(config)# vlan 10 (create VLAN 10 in the VLAN.DAT database)

S1(config-vlan)# name Management (optionally name the VLAN)

S1(config)# interface fa0/12 (select a port on the switch) –or–

S1(config)# interface range fa0/12 – 20 (select a range of ports to be configured the same)

S1(config-if)# switchport mode access (set the port to Access mode)

S1(config-if)# switchport access vlan 10 (assign this port(s) to VLAN 10)

 Trunk Creation

S1(config)# interface gi1/1 (select port for trunking)

S1(config-if)# switchport trunk encapsulation dot1q (NOTE: on Layer 3 switch only)

S1(config-if)# switchport mode trunk (set the port to be in trunk mode)

S1(config-if)# switchport trunk native vlan 99 (set VLAN 99 to carry native traffic)

S1(config-if)# switchport trunk allowed vlan 1,10,20,99 (optional – which VLANs are

permitted to go across this trunk. Don’t forget to include VLAN 1 and the native VLAN)

 Router-on-a-Stick Configuration

R1(config)# interface Fa0/0 (select the main interface)

R1(config-if)# no ip address (there should not be any IP Address on the main interface)

R1(config-if)# interface Fa0/0.10 (create a sub-interface – the number can be anything)

R1(config-if)# encapsulation dot1q 10 (use 802.1Q trunking; assign to this VLAN #)

R1(config-if)# ip address (define the default-gateway IP)

R1(config-if)# interface Fa0/0.99 (create another sub-interface – this one for native traffic)

R1(config-if)# encapsulation dot1q 99 native (802.1Q trunking; VLAN #; and native)

(NOTE: No IP address unless workstations or management interfaces are on this VLAN)

R1(config)# ip classless (classless routing behavior – default in IOS 11.3+)

R1(config)# no ip classless (classful routing behavior)

 VLAN Trunking Protocol (VTP) Configuration

S1(config)# vtp mode server (configure this switch to be in server mode) –or–

S1(config)# vtp mode client (configure this switch to be in client mode) —or–

S1(config)# vtp mode transparent (configure this switch in transparent mode – Suggested)

S1(config)# vtp domain NAME (change the VTP domain name of this switch to NAME)

S1(config)# vtp password PASSWORD (change the VTP password for this switch)

S1(config)# vtp pruning (activate VTP pruning – Not supported in Packet Tracer)

S1(config)# vtp version 2 (change the VTP version to 2)

S1# show vtp status (see VTP mode, revision, version, domain name, pruning mode, etc)

S1# show vtp password (only way to see the VTP password – does not show in status)

 Etherchannel (PortChannel)

 To configure a Layer 2 (trunking) Etherchannel:

S1(config)# interface range fa0/1 – 4 (group of physical interfaces)

S1(config-if)# switchport trunk encapsulation dot1q (NOTE: on Layer 3 switch only)

S1(config-if)# switchport mode trunk (set to trunk mode)

S1(config-if)# switchport trunk native vlan 777 (Set native VLAN)

S1(config-if)# channel-protocol lacp (set this interface to LACP portchannel) -or–

S1(config-if)# channel-protocol pagp (set this interface to PAgP portchannel)

S1(config-if)# channel-group 3 mode [see choices below]

  a. passive (enable LACP only if a LACP device is detected)

  b. active (enable LACP unconditionally)

  c. auto (enable PAgP only if a PAgP device is detected)

  d. desirable (enable PAgP unconditionally)

  e. on (enable Etherchannel)

 S1(config)# interface port-channel 3 (configure the virtual interface from 1 to 6)

S1(config-if)# switchport mode trunk (set to trunk mode)

S1(config-if)# switchport trunk native vlan 777 (set native VLAN the same as the physical)

S1(config-if)# no shutdown (turn on the virtual interface)

To configure a Layer 3 Etherchannel:

SW1(config)# interface range fa0/1 – 2

SW1(config-if)# no switchport

SW1(config-if)# channel-group 1 mode {active, passive, on}

SW1(config)# interface port-channel 1

SW1(config-if)# no switchport

SW1(config-if)# ip address x.x.x.x m.m.m.m

(The other end is configured the same)

 EtherChannel uses a load-balancing algorithm based on selected type or criteria:

> Source IP Address (src-ip)

> Destination IP Address (dst-ip)

> Both Source and Destination IP (src-dst-ip) – default L3 type

> Source MAC address (src-mac) – default L2 type

> Destination MAC address (dst-mac)

> Both Source and Destination MAC (src-dst-mac)

> Source TCP/UDP port number (src-port)

> Destination TCP/UDP port number (dst-port)

> Both Source and Destination port number (src-dst-port)

SW1(config)# port-channel load-balance TYPE

 Spanning Tree Protocol (STP), HSRP

 Spanning Tree

S1(config)# spanning-tree mode pvst (configure for PVST – Default)

S1(config)# spanning-tree mode rapid-pvst (configure this switch for rapid PVST)

S1(config)# spanning-tree vlan 10,20 root primary (make root bridge for these VLANs)

S1(config)# spanning-tree vlan 10 root secondary (make secondary root bridge for VLAN)

S1(config)# spanning-tree vlan 10 priority 8192 (set the BID priority to 8192 in this VLAN)

S1(config)# spanning-tree portfast default (default Portfast on all interfaces in this switch)

S1(config)# interface range fa0/10 – 20 (must be configured as Access ports for Portfast)

S1(config-if)# spanning-tree portfast (set interfaces for Portfast)

S1(config-if)# spanning-tree bpduguard enable (disables interface if it receives a BPDU)

S1(config)# interface fa0/1 (select a port to set STP port priority)

S1(config-if)# spanning-tree vlan 10 port-priority 16 (set port priority to 16; default is 128)

S1# show spanning-tree (see spanning-tree status on a VLAN-by-VLAN basis)

S1# show spanning-tree vlan 10 (see detail spanning-tree information for VLAN 10)

S1# show spanning-tree summary (among other things, see if this is the root bridge)

S1# show spanning-tree blockedports (see which ports are in STP blocking status)

S1# show spanning-tree root (see which BID is root on a VLAN-by-VLAN basis)

 Hot Standby Routing Protocol (HSRP) for IPv4

R1(config)# interface fastethernet 0/1

R1(config)# standby version 2 (use the same version at each end)

R1(config-if)# standby [optional group#] ip [optional IP-ADDRESS] [optional secondary]

(The other end is configured the same)

R1(config-if)# standby [optional group#] priority NUMBER [optional preempt]

Set a higher priority (default 100) to make this router the primary in HSRP

Preempt will make this router the active one if it had been down and comes back up

 Hot Standby Routing Protocol (HSRP) for IPv6

R1(config)# interface fastethernet 0/1

R1(config-if)# standby version 2 (use the same version at each end)

R1(config-if)# standby GROUP# ipv6 autoconfig (create virtual IPv6 Link-Local address)

R1(config-if)# standby GROUP# ipv6 2001:CAFE:ACAD:4::1/64 (set virtual shared IP)

(The other end is configured the same)

R1(config-if)# standby GROUP# priority NUMBER [optional preempt]

Set a higher priority (default 100) to make this router the primary in HSRP

Preempt will make this router the active one if it had been down and comes back up

R1# show standby (verify the configuration)

 Security Practices


R1(config)# service password-encryption (encrypt all passwords (except ‘secret’)

R1(config)# security password min-length 8 (set minimum 8 character passwords)

R1(config)# login block-for 120 attempts 3 within 60 (block for 2 minutes if more than 3

failed logins within 60 seconds)

 SSH Configuration

Router(config)# hostname R1 (must change the name of the device from the default)

R1(config)# username Bob password Let-me-in! (configure a local user and password)

R1(config)# ip domain-name ANYTHING.COM (must set for crypto-key generation)

R1(config)# crypto key generate rsa (make an encryption key – select 1024 bits)

R1(config)# ip ssh version 2 (configure for SSH version 2)

R1(config)# line vty 0 15 (change parameters for remote access)

R1(config-line)# login local (select to authenticate against usernames in this device)

R1(config-line)# transport input ssh (only allow SSH for remote management)

 Port Security Configuration on a Switch

S1(config)# interface fa0/1 or interface range fa0/1 – 15, gi1/1

S1(config-if)# switchport mode access (must change from dynamic to access mode)

S1(config-if)# switchport port-security (must do to activate port-security)

S1(config-if)# switchport port-security maximum 25 (allow 25 MAC addresses)

S1(config-if)# switchport port-security mac-address sticky (memorize MAC addresses)

S1(config-if)# switchport port-security violation restrict (send SNMP message) –or–

S1(config-if)# switchport port-security violation protect (only stop excess MACs) –or–

S1(config-if)# switchport port-security violation shutdown (shutdown interface – default)

S1(config-if)# switchport protected (does not allow traffic to/from other protected ports)

S1(config-if)# spanning-tree bpduguard enable (disables interface if it receives a BPDU)

S1(config-if)# shutdown then no shutdown (restore individual interface if it has shutdown)

S1# errdisable recovery cause psecure_violation (restore shutdown interfaces in 5 min)

S1# show port-security interface fa0/12 (show security configuration for an interface)

 Enable/Disable Cisco Discovery Protocol (CDP)

R1(config)# cdp run (activate CDP globally in the router – on by default)

R1(config)# no cdp run (disable CDP within the entire router)

R1(config-if)# no cdp enable (stop CDP updates leaving through this specific interface)

 IP DHCP Snooping

R1(config)# ip dhcp snooping (globally enable DHCP snooping)

R1(config-if)# ip dhcp snooping trust (interface with DHCP server)

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